Things will only get worse under Trump’s sanctions, but China, India, and other countries are still defiantly buying oil.

Since last year, the United States has been ramping up economic pressure on Iran and has plans to redouble the pain later this spring with even tighter sanctions. Will that financial chokehold be enough to strangle the Iranian economy and bring America’s bête noire to heel?

The balance of expert opinion is that there is still a lot of resistance left in Iran’s oft-proclaimed “resistance economy.” While it is hurting badly and is more vulnerable today than during the last period of prolonged U.S. sanctions, from 2012 to 2015, Iran’s economy is not nearly as dysfunctional as that of Venezuela, another target of U.S. sanctions meant to weaken the longtime ruling regime. U.S. sanctions there threaten to absolutely cripple Venezuela’s ability to pump and export oil, essentially cutting off all government income.

“The [Iranian] economy is much more resilient than some hawks in the White House and Washington in general seem to assume, but things are bad and are going to get worse,” said Henry Rome, an Iran analyst at Eurasia Group. That doesn’t mean, however, that the regime is one good push away from collapse.

“U.S. unilateral sanctions are causing real pain to the Iranian economy—much more than many had predicted,” Rome said. “But today we are nowhere near full economic collapse or a genuine threat to regime survival.”

U.S. pressure on Iran, made patent since last year’s withdrawal from the 2015 nuclear deal, was showcased again on Wednesday at the start of a two-day, 60-country conference in Warsaw, Poland, meant to tap into growing European frustration with Iran’s bad deeds. But the absence from the Warsaw conference of Europe’s major players—including France and Germany and the European Union itself—also underscored the degree to which Washington is largely going it alone on its maximum pressure campaign on Tehran.

The bad news for Iran is that, just a few months after U.S. sanctions on oil exports kicked back in, the economy is in miserable shape. The currency has depreciated, inflation is rampant, and unemployment is high, while GDP contracted last year and looks set to shrink even further this year. Dwindling oil exports have cut into government revenues, and U.S. sanctions on financial transactions have chilled economic activity in a number of other sectors, including autos and humanitarian goods like food and medicine.

“The economy is even worse than they let on,” said Alireza Nader, the CEO of New Iran, a research and advocacy organization in Washington. Iran’s once proud auto industry is on the verge of collapse, and while Iranian Central Bank officials have managed to stabilize the exchange rate, it came at the cost of draining foreign reserves. Meanwhile, shortages of meat and basic medicines are fueling popular frustration. “This idea of the resistance economy is totally false,” Nader said.

The really scary news for Iran is that the full brunt of U.S. sanctions has really just begun to be felt, with limits on Iranian oil exports becoming effective only last November. The U.S. economic pressure is simply adding to years of corruption and economic mismanagement by Iran’s leadership, which has led to chronic inflation, unemployment, and failed efforts to turn Iran into a welcoming place for foreign investment. Coupled with lower average oil prices now than during the Obama administration, when the United States sharply limited Iran’s crude exports, that means Tehran has less ability to absorb U.S. sanctions than in the past.

Last year’s budget deficit, for example, turned out to be twice as big as the government forecast—and that was with higher than expected revenues from oil exports. What happened was that other sources of revenue fell short of expectations as the economy contracted. Lower government revenues meant a bigger deficit, which in turn pushed down the value of the Iranian currency and made imports more expensive.

This year’s budget is even more problematic, premised on the idea that Iran will export 1.5 million barrels of oil a day despite U.S. sanctions. (Exports have dropped from about 2.5 million barrels a day before sanctions to just over 1 million barrels a day currently.) The budget plan, Rome said, appears to increase Iran’s reliance on oil revenues just as its ability to export even modest amounts is under threat, and it has trouble getting paid for what it does manage to sell.

U.S. officials are hoping to home in on that growing vulnerability. Brian Hook, the State Department’s special envoy for Iran, said last month that the administration would not issue waivers for countries to keep buying Iranian oil. Last fall, when the sanctions went back into place, the Trump administration gave countries including China, India, Japan, and South Korea permission to keep buying some Iranian oil. Those waivers expire in May—and the administration insists that this time it will drive Iran’s crude exports close to zero.

That may be wishful thinking. China and India, Iran’s two biggest customers, have so far resisted U.S. calls to sharply reduce their purchases of Iranian oil; New Delhi, in particular, has strategic reasons to keep on good terms with Tehran. And U.S. sanctions on Venezuela’s oil production and exports will likely cause a shortage of the kind of heavy oil that both countries produce, giving U.S. policymakers that much less room to further squeeze Iran’s heavy oil exports.

But even if the United States grants additional waivers in May for countries to keep buying Iranian oil at close to current levels, Iran’s economic pain this year will get worse. The International Monetary Fund expects the economy to shrink by more than 3 percent, as foreign investment dries up and Iranian industries struggle to purchase goods they need to stay in business. Iran is already expecting a hefty budget deficit even with its rosy projections of oil exports; if those fall below expectations, the country would have to cut salaries and social spending, raise taxes, or fuel inflation. None of those options is appealing a year after massive economic protests rocked the country.

But will Iran’s economic pain translate into a policy win for the Trump administration, which seeks at a minimum to change Iran’s foreign-policy behavior, if not topple the regime outright?

Nader doesn’t think that an economic collapse by itself will imperil Iran’s leaders unless that is coupled with more organized domestic opposition. Still, he senses in the widespread popular unrest what he calls a “pre-revolutionary mood.” Many Iranians are irate at President Hassan Rouhani’s handling of the economy, as well as other issues from women’s rights to water management. “It doesn’t look good for this regime,” he said.

But Iran, which this week is celebrating the 40th anniversary of the Islamic Revolution, has demonstrated staying power even in adversity and usually responds to Western pressure by doubling down on objectionable behavior.

“Iran is cementing its regional gains and completely defying calls from Western countries to rein in its missile program,” said Ellie Geranmayeh, the deputy director of the Middle East and North Africa program at the European Council on Foreign Relations.

Since the 1979 revolution that toppled the shah and launched the Islamic Republic, Iran has been in a U.S. economic squeeze—yet the country has only ramped up its support for regional terrorist groups and sown instability throughout the region. Even now, despite renewed U.S. sanctions, Iran has pressed ahead with missile tests and satellite launches, as well as continued to support proxies in Syria and Yemen.

Even though Europe has so far been unable to throw Iran a real lifeline so far to evade sanctions, Washington has been unable to translate that pressure into a more compliant Tehran.

“The U.S. maximum pressure campaign is full on, but we’re not seeing the type of results that the Trump administration hoped for,” Geranmayeh said.